Opening behaving badly..

[Graeme]

I've used the Opening tool to add holes for ductwork through my partitions. What is weird is that a lot of these Openings are behaving badly or weirdly as their width and height are swapped around and I can't find a reason why.

The screenshots show two openings one behaving correctly and the other with the weird behaviour namely when you enter the width the height changes and same if you enter the height the width changes.